The invention relates to a method and a computer program for identifying when a driver of a vehicle, in particular a motor vehicle, is not paying attention during operation of the vehicle. The invention also relates to a data storage medium having stored thereon such a computer program.
Various proposals for detecting inattentiveness by a motor vehicle driver, in particular a tendency for the motor vehicle driver to go to sleep, are known from the prior art.
By way of example, one corresponding proposal is disclosed in German Laid-Open Application DE 198 18 239 A1. The apparatus disclosed there for warning that a motor vehicle driver is going to sleep comprises firstly a vehicle environment identification device for detection of the actual driving style of the motor vehicle driver. The apparatus described there also comprises a device for detection of a reference driving style, in particular detecting how many lateral self-movements there normally are by the motor vehicle driver in his driving style. Finally, the disclosed apparatus has comparison logic for comparison of the reference driving style with the current actual driving style in order to output a warning to the motor vehicle driver on the basis of the result of this comparison.
Furthermore, a method and an apparatus for determination of the stress of the driver of a motor vehicle are known from U.S. Pat. No. 6,061,610. This method provides for the steering wheel angle of the motor vehicle to be detected first of all in order from this to generate prediction errors for the steering wheel angle in the driver's control of the motor vehicle. A distribution of these prediction errors is then calculated in order to compare this distribution with another distribution of prediction errors of the steering wheel angle which does not represent the real steering behavior of the driver, but represents a predetermined steering behavior of a stress-free or unstressed driver. The result of this comparison then represents the current stress on the driver while driving the motor vehicle.
Finally, German Laid-Open Application Del. 25 46 345 discloses a driver warning device for warning motor vehicle drivers before they go to sleep. The device detects the steering movement of the driver of the motor vehicle, on the assumption that, when the driver is awake, the steering wheel is not held entirely at quiescent even when traveling in a straight line but that steering movements are also carried out continuously then, even if they are still very small. If the driver warning device detects absence of these steering movements over an adjustable time interval, as well, then the driver warning device deduces from this that the driver is going to sleep, or is at least at risk of going to sleep, and then warns the driver by outputting a signal.
The driver warning device disclosed in the last-mentioned Laid-Open Application DE 25 46 345 has a disadvantage in that the decision on when the driver of a vehicle is not paying attention is made solely on the basis of the detection of a steering quiescent phase, and that this decision can, therefore, be made only quite vaguely and unreliably.
Against the background of this prior art, the object of the invention is, therefore, to provide a method and a corresponding computer program in order to identify when the driver of a motor vehicle is not paying attention, as well as a controller for carrying out this method and a data storage medium storing such a computer program, which makes it possible to more reliably identify possible inattentiveness of the driver.
This object is achieved by a method for identifying when the driver of a vehicle, in particular of a motor vehicle, is not paying attention. The method includes detecting any movement of a steering wheel of the vehicle in the form of a steering wheel angle x; and identifying a steering quiescent phase and determining the magnitude of the extent of the steering quiescent phase by evaluating the detected steering wheel angle and/or its rate of change; wherein a steering action is identified following the steering quiescent phase and the magnitude of the extent of the steering action is determined by evaluating the rate of change of the steering wheel angle; and further wherein a measure of the severity of the inattentiveness by the driver is determined while steering the vehicle by assessing the result of a link between the extent of the steering quiescent phase and the extent of the steering action.
In the process of identification of inattentiveness of the driver, the invention—in contrast to the prior art—advantageously distinguishes between a steering quiescent phase and a more or less hectic steering action, which typically follows a state of inattentiveness. Thus, according to the invention, a state of inattentiveness is not assumed at all unless both the steering quiescent phase and the subsequent steering action are identified in conjunction with one another; conversely, this means that just identification of a steering quiescent phase or of a steering action is not sufficient to deduce inattentiveness of the driver. The detected extents of both the quiescent phase and of the steering action are logically linked to one another for determination of the extent of the severity of the inattentiveness, and the result is then assessed.
In modern vehicles, in particular motor vehicles, a sensor for detection of the steering wheel angle x is normally provided in any case. Thus, in principle, no additional sensors are advantageously required to implement the described method.
Two different exemplary embodiments for implementation of the invention will be explained in the description and claimed herein. In principle, a specific way to determine the extent of the steering quiescent phase is provided for a first of the exemplary embodiments; however, this determination process can also be carried out according to a second of the exemplary embodiments.
Further refinements of the method, as are described and claimed herein, apply equally both to the first exemplary embodiment and to the second exemplary embodiment.
Advantages of the First Exemplary Embodiment
Calculation of the extent of the steering action solely by formation of a steering wheel angle variance would merely represent the steering behavior of the driver at one time. However, in order to make a reliable statement on the existence of inattentiveness, it is in fact important to take account of changes in the steering behavior over time, as well. According to the invention, this aspect is taken into account by including two steering wheel angle variances in the formation of the variance ratio, which each represent the steering action of the driver at different times, with the two times being offset through a time interval Δt with respect to one another.
The variance ratio calculated according to the invention can intrinsically advantageously be interpreted as a measure of the severity of the inattentiveness of the driver while steering the vehicle at the time t1; inattentiveness of the driver exists in particular when this variance ratio has a value greater than 1.
Advantage of the Second Exemplary Embodiment
In contrast to the first exemplary embodiment, the second exemplary embodiment makes use of considerably fewer parameters for assessment of the inattentiveness of the driver. It is, therefore, less memory intensive. Furthermore, owing to the use of considerably simpler algorithms, it can be coped with more easily and can be implemented in real-time. Overall, it is therefore highly suitable for practical use in a vehicle.
It is thus advantageous that an assessment of the extent of the steering quiescent phase, that is to say its time duration, is preferably made only by evaluation of the steering wheel angle, and the extent of the steering action is preferably determined only by detection of the maximum steering angle wheel gradient that occurs. There is, therefore, no need for any calculation or evaluation based on the variance function.
Logically linking the extent of the steering quiescent phase to the extent of the steering action in order to determine a measure for the severity of the inattentiveness by the driver is carried out in the second exemplary embodiment by way of a multi-dimensional operator. In order to save unnecessary computation complexity, this logical operation is, however, preferably carried out only when both the steering quiescent phase and the expected subsequent steering action each take place with a predetermined minimum extent. If the steering quiescent phase or the steering action are not sufficiently sharply pronounced, then, according to the invention, it is assumed that the driver is not in a state of inattentiveness.
Advantageous Refinements of the Inventive Method which Both Exemplary Embodiments May Employ
The result of the logical operation from the first or second exemplary embodiment, that is to say the variance ratio or the result of the operator logical operation, can advantageously be mapped onto a probability value with the aid of the sigmoid function. This means that it is possible to specify a probability of the driver having been inattentive in the steering of the vehicle at the time t1 between 0 and 100%.
In a further advantageous refinement, the claimed method based on the previously determined probability value allows a statement to be made on the probability with which the behavior of the driver can be associated with one specific fatigue level, which is suitably selected and is predetermined from a large number of such levels. According to the invention, an association such as this is always made taking into account the currently detected steering wheel angle.
This association with the predetermined fatigue levels can advantageously be made more precise by taking into account not only the steering wheel angle as a first indicator, but also further observable indicators for the inattentiveness by the driver, such as his eyelid closure behavior or his reaction time.
It is also advantageous that the estimate of the fatigue of the driver can also be made more precise by taking account for this estimate not only the currently detected values of, in particular, the stated indicators, but also the fatigue classifications carried out in the recent past. In other words, this procedure allows a plausibility check of the new estimate taking into account the fact that the driver fatigue is not a phenomenon which occurs or disappears again suddenly, but which in fact changes only continuously over the course of time.
The inventive method advantageously allows not only, as described above, a conclusion to be drawn about driver fatigue as the cause of the detected inattentiveness. In fact, it also allows a conclusion to be drawn relating to other causes for the detected inattentiveness, which, for example, may lie in a conversation being held with a front seat passenger or the operation of an apparatus, such as the radio or the glove compartment in the vehicle.
In order to improve the reliability of a statement relating to the attention level or inattentiveness of the vehicle driver, it is worthwhile evaluating not only a result of the logical operation according to the first or second exemplary embodiment but, instead of this, for this statement to be based on a large number of such logical operation results. In this case, this plurality may include not only merely results from the first or from the second exemplary embodiment, but also a mixture of results from the first and from the second exemplary embodiment. Specifically, a statement can be made more reliably about the inattentiveness by the driver by weighting each result obtained from a logical operation with an associated weighting factor in order then to obtain an averaged logical operation result in the final analysis from the present plurality of weighted logical operation results, by mathematical averaging. This averaged logical operation result then represents a more reliable measure than a non-averaged logical operation result of the severity of the inattentiveness by the driver in the steering of the vehicle at a specific time.
Finally, it is advantageous, in particular, for the driver of the vehicle to be informed of the identified inattentiveness in the form of visual or audible warning information.
Further advantageous refinements of the method are described and claimed herein.
The object of the invention as mentioned above is also achieved by a computer program for carrying out the described method, by a data storage medium with the computer program, and by a controller for carrying out the described method. The advantages of these solutions correspond to the advantages mentioned above with respect to the described method.
This computer program advantageously need be programmed only once at least for individual vehicle types, and can then be implemented in all the vehicles of a corresponding model.